Many construction tasks require the application of hardenable materials. The term “hardenable” is used herein to refer materials that dry upon exposure to air such that they are no longer flowable. A hardenable material that has dried upon exposure to air may retain some resiliency; the term “hardenable” thus does not necessarily suggest that a hardenable material is rigid or unyielding when dry.
The types of hardenable materials employed during construction tasks include caulking materials, construction adhesives, and the like. These types of hardenable materials are typically viscous upon manufacture and remain flowable when not exposed to air. Typically, the hardenable material is formulated such that the material is no longer flowable anywhere from five minutes to two hours after exposure to air. Accordingly, hardenable materials used during construction are typically manufactured, shipped, and sold in a sealed storage container. Immediately prior to use, a dispensing opening is formed in the sealed storage container through which the hardenable material may be dispensed.
Some hardenable materials may be dispensed directly from the storage container. For example, certain caulking materials are sold in a deformable tube having an integral dispensing tip. Once the dispensing tip has been cut to form a dispensing opening, the tube is squeezed to dispense the caulking material through the dispensing opening.
For a variety of reasons, other hardenable materials can not be easily or conveniently dispensed by applying pressure directly to the storage container. Some hardenable materials are simply too viscous to be dispensed by direct hand pressure to the container. Other hardenable materials must be dispensed in relatively large quantities, and the use of direct hand pressure can cause operator fatigue.
Accordingly, many hardenable materials are dispensed using a dispensing system comprising dispensing gun and a product cartridge. A dispensing gun uses a lever to displace an actuator rod that forces the hardenable material out of the product cartridge. The operator applies hand pressure to the lever which in turn acts on the rod, thereby creating a mechanical advantage that assists in the dispensing of the material. Typically, dispensing guns allows highly viscous materials to be dispensed using hand pressure. Dispensing guns can also allow an operator to dispense relatively larger quantities of the hardenable material without fatigue. Some types of dispensing guns may assist the operator using electric, hydraulic, pneumatic, or other systems for generating mechanical forces.
When a hardenable material is to be dispensed using a dispensing gun, the hardenable material is typically stored in the product cartridge prior to use. The product cartridge typically comprises a paperboard cylinder, a dispensing tip, and a floating piston member. The dispensing tip is attached to a first end of the cylinder, and the piston member is initially position within the cylinder adjacent to a second end thereof. When originally manufactured, the entire cartridge is substantially air tight to prevent the hardenable material from drying prior to use.
Immediately prior to use, the cartridge is placed in the dispensing gun with the piston member adjacent to the actuator rod. The dispensing tip is also cut or pierced to form a dispensing opening. The operator arranges the dispensing opening adjacent to the surface where the material is to be dispensed. The operator then applies manual force to the lever. The lever forces the actuator rod against the piston member, is which in turn applies pressure to the hardenable material. The pressure on the hardenable material causes the hardenable material to flow out of the dispensing opening.
Once the dispensing opening has been formed, the cartridge is no longer air-tight. In particular, the hardenable material in the dispensing tip adjacent to the dispensing opening is in direct contact with the air. If the material within the dispensing tip is allowed to dry out, the dispensing opening may become blocked, and the entire cartridge may be unusable.
As long as the operator continues to operate the dispensing gun, the hardenable material in the dispensing tip does not have a chance to dry out. Often, however, the operator will be interrupted while using a dispensing gun with an opened cartridge of hardenable material. If the interruption is longer than the drying time of the hardenable material, the dispensing opening may become blocked and the cartridge may become unusable. Typically, an operator will simply discard a cartridge that has become blocked regardless of how much material remains within the cartridge. A similar situation occurs at the end of the day or when the operator completes a job.
Another problem with existing dispensing systems arises from the back pressure created by the relatively viscous hardenable materials. When the lever is actuated to displace the actuator rod and piston member, a relatively high pressure zone is created within the cartridge. The viscosity of the hardenable material typically creates a back pressure that causes the high pressure within the cartridge to decay over time. Accordingly, the pressure within the cylinder persists after the pressure is no longer applied by the piston member. This residual pressure continues to cause the hardenable material to flow out of the dispensing opening after the operator has stopped actuating the lever. The operator must wait for the residual pressure to dissipate or find a place where excess hardenable material can be dispensed. The flow of dispensing material caused by residual pressure within the cartridge can thus reduce the productivity of the operator.
Another problem with conventional dispensing systems is where to put the dispensing gun when not in use. For example, an operator could be using a construction adhesive while framing a house. In this case, the operator may apply the adhesive to secure one step board to another nail the two boards together, and then fetch the next board. When the operator is nailing the first two boards together and fetching the next board, the dispensing gun must be temporarily stored at an out of the way location until the adhesive is to be used with the next board. This temporary storage is complicated by the continued flow of material caused by residual pressure within the cartridge.
From the foregoing, it should be apparent that the need exists for systems and methods for holding dispensers for hardenable materials.